1. Field of the Invention:
This invention relates to apparatus and method for handling flat articles such as documents, envelopes, cards and the like, and more particularly to apparatus and method for receiving documents individually sequentially edge-on at a high celerity and stacking the documents adjacently side-on-side.
2. Prior Art and Other Considerations:
Machines for automatically handling documents such as mailing envelopes at high celerities find increasingly widespread use in commercial and governmental institutions. Among such machines are those that are adapted to receive documents which are singly delivered thereto at a high velocity and that stack the documents side-on-side so that they are orderly arranged in a stack.
Problems are often encountered in automatically stacking documents at high speeds. For example, rapid accelerations and decelerations, together with various frictional effects encountered in the course of the transition from sequential feed to the stacking mechanisms while the documents are being variously engaged and disengaged, can cause binding or buckling and can damage documents. Moreover, misalignment during stacking may cause damage to the documents. For instance, if side-on-side sliding of envelopes occurs during stacking, envelopes can become torn. Window-type mailing envelopes are particularly susceptible to tearing near the window, which not only damages the envelope itself, but may also cause jamming in the stacking apparatus, possibly necessitating shut-down of the device.
Prior art stacking devices employing helical or screw-type device for the transfer of individually sequentially fed articles into stacks are known. For instance, U.S. Pat. No. 277,806 to Stonemetz et al shows a packing device that comprises a revolving helix device that receives papers, envelopes and the like edgewise between the coils of its helix and conveys these, as it revolves, broadsidewise to a bench.
U.S. Pat. No. 3,160,293 to Hennequin discloses a rotatable circular disc with a cut-out that has one side-wall warped out of the plane of the disc so as to provide a vane. The vane is in the general form of a portion of a helicoid projecting from the side of the disc against which each elementary stack of letters is to be formed.
Another prior art stacking device shown in U.S. Pat. No. 4,378,938 to Staniszewski discloses a mechanism using counter-rotating helical stacker members. U.S. Pat. Nos. 3,280,679 (Huffman), 3,847,382 (McKee), and 3,995,851 (Casper) also show screw-like devices for handling, engagement, or transporting of documents.
U.S. patent application Ser. No. 07/109,058, entitled Document Stacking Apparatus and commonly assigned herewith, is incorporated herein by reference as disclosing an apparatus wherein upper and lower rotatable stacking screw worms move documents laterally away from a carriage into stacked relationship. Sensing means such as an electric contact switch or a photoelectric cell can be used to detect horizontal movement of the stacking apparatus.
In view of the foregoing, it is an object of the present invention to provide apparatus and method for automatically stacking documents at high celerities.
An advantage of the present invention is the provision of apparatus and method for automatically stacking documents at high celerities that avoids side-on-side sliding of documents and jamming of the device.
A further advantage of the present invention is the provision of improved apparatus and method for automatically stacking documents at high celerities that utilizes a helix device having non-uniform leads for stacking and provides for substantial independence of operation of the helix device in respect to interdocumental pressure variations in the stack.
Another advantage of the present invention is the provision of document stacking apparatus that utilizes drive components of the document feeding device to facilitate and assist reliable and orderly document stacking.
Yet another advantage of the present invention is the provision of improved apparatus and method for automatically stacking documents at high celerities that utilizes a helix device that is automatically clutched for one revolution at a time in dependence on and under control of the sensing of injection of a document.
Yet a further advantage of the present invention is the provision of improved apparatus and method for automatically stacking documents at high celerities that utilizes a document feeding section that is adjustable to feeding different sizes of documents and a document stacking apparatus section that is adjustable to receiving, stacking, and accumulating such different sizes of documents.
Another advantage of the present invention is the provision of a document feeding section including photosensors and associated control circuitry for automatic document jam detection therein.